1. Field Of The Invention
This invention relates to novel silicone polymers which are swollen with silicone oils and also to pasty silicone oil compositions which comprise the silicone polymers and silicone oils and are capable of stably and uniformly dispersing water therein.
2. Description of The Prior Art
Silicone oils are non-toxic and have thus wide utility in various fields including medicines and cosmetics, as base oils for a variety of compositions. In general, silicone oils have a relatively high viscosity of not lower than 100 centistokes at 25.degree. C. Especially, in the fields of medicines and cosmetics, attention has been recently drawn to silicone oils which have a low viscosity of not higher than 100 centistokes because of their good extensibility, cool or refreshing touch and high safety. Hence, extensive studies have been made on the applications of such silicone oils.
However, when low viscosity silicone oils are used as a base oil to prepare, for example, pasty or greasy compositions, it is necessary to add thickening agents in amounts larger than in the case using ordinary silicone oils. This makes it difficult to obtain a homogeneous, uniform composition, with the attendant problem that the low viscosity silicone oil is liable to separate from the composition with low stability of the composition.
In order to solve these problems, attempts have been heretofore made wherein various types of thickening agents for the low viscosity silicone oils are proposed including organic materials such as fatty acid esters of dextrin (Japanese Laid-open Application Nos. 62-121764, 62-143971, 62-143970 and 63-159489), fatty acid esters of sucrose (Japanese Laid-open Patent Application No. 63-235366), trimethylsilylated polyvinyl alcohol or trimethylsilylated polysaccharides (Japanese Laid-open Patent Application No. 62-240335), fatty acid ester group-containing cellulose ethers (Japanese Laid-open Patent Application No. 63-260955) and the like, and inorganic materials such as organic modified clay minerals (Japanese Laid-open Patent Application Nos. 62-45656, 62-54759 and 63-72779).
However, the use of these organic or inorganic materials as a thickening agent involves the problem that the inherent characteristics of the silicone oil such as the refreshing or cool touch to the skin and the high extensibility are reduced.
Another approach has been proposed, for example, in Japanese Laid-open Patent Application No. 2-43263, wherein a specific type of silicone polymer is provided as a thickening agent and treated along with low viscosity silicone oils under shearing conditions to obtain a uniform pasty composition.
In the fields of medicines and cosmetic articles, there are often used compositions which are formulated not only with oils, but also with water as essential ingredients. In such a case, it is usual to add surface active agents to the composition. However, a difficulty is still involved in dispersing silicone oils and water uniformly and stably. In addition, most surface active agents are irritative to the skin and their use is not favorable. Although the silicone thickening agent set forth in the Japanese Laid-open Patent Application No. 2-43263 exhibits good thickening properties against silicone oils, water is not uniformly dispersed therein.